1. Field of the Invention
The present invention relates to an interposer on which discrete parts such as capacitors are mounted, and to a semiconductor device including the interposer.
2. Description of Related Art
Power supply noise is generated in electronic parts such as a CPU and a clock driver. To reduce the power supply noise, generally, capacitors are employed.
When the frequency of the power noise becomes higher, the capacitors need to be mounted closer to the electronic parts. However, such locations for mounting the capacitors are limited to peripheral rooms of the electronic parts or the back side of an electronic part 104 mounted on an interposer 101 as shown in FIG. 12. Therefore, it is impossible for a capacitor 103 to be placed any closer to the electronic part 104.
Further, as shown in FIG. 13, a cavity is formed from the back surface of the interposer 101 or the print wiring board to the middle of the wiring layer, and a cavity portion :102 is mounted with the capacitor 103. This structure is proposed so that the capacitor 103 can be disposed at a position closer than the electronic part 104. However, with this structure, the wiring path where the cavity is formed across the wiring layers is broken. As a result, the capability of power supply is reduced, and the wiring arrangement of signal lines is degraded.
Furthermore, for example, Japanese Patent Application Publication No. 2009-59822 describes that a high dielectric material is sandwiched between a power supply layer and a ground layer of an interposer or a print wiring board to form a capacitor sheet in it. However, this capacitor sheet has a small capacitance compared to that of general capacitors, so that there is a problem in that the power supply noise cannot be reduced sufficiently.